1. Field of the Invention
The invention pertains to a method and an apparatus for milling or cutting pairs of bevels arranged symmetrically about the longitudinal axis of halving joints or similar members for windows, glass doors, and the like, as well as a groove-like recess lying between two pairs of bevels on opposite sides of the workpiece.
2. Description of the Prior Art
For milling or cutting bevels symmetrically about the center axis of halving joints, automatically operated milling machines of high efficiency are known. Such machines operate with one cutting unit per pair of bevels, so that the two pairs of bevels to be machined on opposite sides of the halving joint are milled simultaneously. This requires two separate milling units, which are independent from each other, one of which is arranged above the workpiece and the other below the workpiece. The cost of this type of automatic machine is rather high, so it can only be used economically if high production is required. However, for smaller firms, or if limited output rates will be sufficient, or if production is on an occasional basis, the high cost of such a machine is not justified.
For these lower production types of use, the cutting of bevels on halving joints for wooden frame portions and of grooves at the connections of the halving joints is ordinarily made in such a manner that at first, a bevel is cut into the workpiece while it is fastened on a clamping device; then the workpiece is released, turned 180.degree., fastened again, and the opposite bevel is milled. Subsequently thereto, the workpiece is released and fastened once more for the grooving operation. Repeated fastening and releasing of the workpiece causes considerable inaccuracies in operation, because the workpiece, after having been released, turned and refastened, is no longer in its original position, so that the two bevels may not be milled exactly symmetrically to the halving joint axis and thus, the required exact fit will be lost. Such inaccuracies can be reduced only by releasing and refastening the workpiece in a very careful manner, which requires considerable time, care and skill on the part of the operator.